1. Field of the Invention
This invention relates to a rotary piston, internal combustion engine having a rotary piston eccentrically mounted for rotation in a multi-lobe, trochoidal-shaped engine housing and defining, with the housing, intake, compression, expansion and exhaust working chambers, each of which varies in volume as the rotary piston rotates within the housing in combination with ignition means for initiating fuel combustion disposed within the housing at a point relative to the direction of rotary piston rotation preceding the lobe junction between the compression and expansion combustion-working chambers. The rotary engine utilizes a premixed charge of fuel and air as opposed to a stratified charge. To provide the desired compression ratio, the rotary piston is provided with a rotor recess in each peripheral rotary surface. With known rotor recesses, or pockets, the mixture within the pocket may burn completely while the portions of the charge in the leading, trailing and side edge regions are not completely burned due to quenching. This invention comprises a rotary piston having a pocket design which reduces the volume of the quench zones relative to the quench zones of a rotor having a standard pocket. As a result, the fraction of premixed fuel/air charge that burns completely is substantially greater than with standard rotors. This, in turn, reduces the amount of unburned hydrocarbons emitted through the exhaust and, thus, increases efficiency of the engine. The underlying principal of this invention is that, for premixed charges, the pocket should occupy as great a fraction of the surface of the peripheral surface of the rotor as possible for reduced emissions and increased efficiency.